Be cautious to talk poorly about your team mates, boss or industry.
Think of perceptive questions to express that you're curious and have thought about the opportunity.
Make a Google Alert on the firm to know latest developments.
Read about the company, manager, and job opportunity.
Do not go off topic. Keep your thoughts on the things you are good at.
Advice for those looking for employment:
"The search for a new job starts with you writing down your ideals, specialities, prowess, and objectives. How are you to get a role if you are not clear of what you require a job to be and what you are able to do for a potential firm?"